Mobile applications, mobile apps for short, have proven their usefulness in enhancing service provisioning across a multitude of domains that range from smart healthcare, to mobile commerce, and areas of context sensitive computing. In recent years, a number of empirically grounded, survey-based studies have been conducted to investigate secure development and usage of mHealth apps. However, such studies rely on self reported behaviors documented via interviews or survey questions that lack a practical, i.e. action based approach to monitor and synthesise users actions and behaviors in security critical scenarios. We conducted an empirical study, engaging participants with attack simulation scenarios and analyse their actions, for investigating the security awareness of mHealth app users via action-based research. We simulated some common security attack scenarios in mHealth context and engaged a total of 105 app users to monitor their actions and analyse their behavior. We analysed users data with statistical analysis including reliability and correlations tests, descriptive analysis, and qualitative data analysis. Our results indicate that whilst the minority of our participants perceived access permissions positively, the majority had negative views by indicating that such an app could violate or cost them to lose privacy. Users provide their consent, granting permissions, without a careful review of privacy policies that leads to undesired or malicious access to health critical data. The results also indicated that 73.3% of our participants had denied at least one access permission, and 36% of our participants preferred no authentication method. The study complements existing research on secure usage of mHealth apps, simulates security threats to monitor users actions, and provides empirically grounded guidelines for secure development and usage of mobile health systems.